Lending App example

lending-app/README.md

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+# Lending Protocol on CCF Framework
+
+## Overview
+This is a decentralized lending protocol built on the Microsoft CCF framework. The protocol enables:
+- **Collateralized Lending**: Users can deposit BTC or ETH as collateral and borrow USDT.
+- **Liquidity Pool Management**: Users can add or remove liquidity from BTC and ETH pools.
+- **Interest Distribution**: Liquidity providers earn DEFI tokens as interest rewards.
+
+---
+
+## Features
+- **Collateral Management**:
+  - Deposit BTC or ETH as collateral to borrow USDT.
+  - Collateral factor applied for safe borrowing limits.
+
+- **Liquidity Pools**:
+  - BTC and ETH pools for providing liquidity.
+  - Interest distributed to liquidity providers in DEFI tokens.
+
+- **Wallet Operations**:
+  - Deposit and withdraw tokens.
+  - Query wallet balances.
+
+---
+
+## API Endpoints
+### Wallet Endpoints
+- **Deposit Token**: `/wallet/deposit`
+- **Withdraw Token**: `/wallet/withdraw`
+- **Get Wallet Balance**: `/wallet/balance`
+
+### Lending Endpoints
+- **Add Collateral**: `/lending/collateral/add`
+- **Borrow Tokens**: `/lending/borrow`
+- **Remove Liquidity**: `/lending/liquidity/remove`
+
+---
+
+## Configuration
+- **Collateral Factor**: Default `1.5` (borrow limit = collateral / collateralFactor).
+- **Base Interest Rate**: Default `2%` per period.
+
+---
+
+## Example Usage
+### Add Collateral
+**Request**:
+```json
+POST /lending/collateral/add
+{
+  "userId": "user1",
+  "symbol": "BTC",
+  "amount": 2
+}
+
+{
+  "statusCode": 200,
+  "body": "Added 2 of token BTC as collateral for user1."
+}
+```
+### Borrow Against Collateral
+**Request**:
+```json
+POST /lending/borrow
+{
+  "userId": "user1",
+  "borrowAmount": 1000,
+  "baseTokenSymbol": "USDT"
+}
+
+{
+  "statusCode": 200,
+  "body": "Borrowed 1000 of token USDT against collateral."
+}
+
+```

lending-app/package.json

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+{
+  "dependencies": {
+    "@microsoft/ccf-app": "^6.0.0-dev11",
+    "typescript": "^5.7.3"
+  },
+  "devDependencies": {
+    "@types/node": "^22.10.5"
+  }
+}

lending-app/src/endpoints/lending.ts

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+import * as ccfapp from "@microsoft/ccf-app";
+import { addCollateral, borrow } from "../modules/lending";
+import { handleError } from "../utils/errorHandler";
+
+
+/**
+ * Handles depositing tokens into the lending protocol for collateral.
+ *
+ * This endpoint allows users to directly add tokens to their collateral,
+ * deducting the specified amount from their wallet balance. The collateral
+ * is used to increase the user's borrowing capacity.
+ *
+ * Input:
+ * - `userId` (string): The unique identifier for the user making the deposit.
+ * - `symbol` (string): The token symbol (e.g., "DEFI").
+ * - `amount` (number): The amount of the token to deposit as collateral.
+ *
+ * Output:
+ * - Success: Returns a success message confirming the collateral addition.
+ * - Failure: Returns an error message with the appropriate HTTP status code.
+ *
+ * Workflow:
+ * 1. Parse and validate the input parameters (`userId`, `symbol`, `amount`).
+ * 2. Check that the user exists and has sufficient balance for the token.
+ * 3. Deduct the specified `amount` of `symbol` tokens from the user's wallet.
+ * 4. Add the deducted tokens to the user's collateral in the lending protocol.
+ * 5. Return a success message confirming the operation.
+ *
+ * Example Request:
+ * ```json
+ * {
+ *   "userId": "user1",
+ *   "symbol": "DEFI",
+ *   "amount": 500
+ * }
+ * ```
+ *
+ * Example Response (Success):
+ * ```json
+ * {
+ *   "statusCode": 200,
+ *   "body": "Added 500 of token DEFI as collateral for user1."
+ * }
+ * ```
+ *
+ * Example Response (Error: Invalid Input):
+ * ```json
+ * {
+ *   "statusCode": 400,
+ *   "body": "Invalid input parameters"
+ * }
+ * ```
+ *
+ * Example Response (Error: Insufficient Balance):
+ * ```json
+ * {
+ *   "statusCode": 400,
+ *   "body": "Insufficient token balance for collateral addition."
+ * }
+ * ```
+ */
+export function addCollateralEndpoint(request: ccfapp.Request): ccfapp.Response {
+    let body;
+    try {
+        body = request.body.json();
+    } catch {
+        return { statusCode: 400, body: "Invalid request body" };
+    }
+
+    const { userId, symbol, amount } = body;
+
+    // Validate input parameters
+    if (!userId || !symbol || amount <= 0) {
+        return { statusCode: 400, body: "Invalid input parameters" };
+    }
+
+    try {
+        // Add tokens directly to collateral
+        const collateralResult = addCollateral(userId, symbol, amount);
+
+        return { statusCode: 200, body: collateralResult };
+    } catch (error) {
+        return handleError(error);
+    }
+}
+
+/**
+ * Handles borrowing tokens against collateral in the lending protocol.
+ *
+ * This endpoint validates the user's collateral and borrowing capacity
+ * before crediting the borrowed tokens to their wallet. The borrow
+ * operation deducts the borrowed amount from the protocol's liquidity
+ * pool and increases the user's debt balance.
+ *
+ * Input:
+ * - `userId` (string): The unique identifier of the user making the request.
+ * - `borrowAmount` (number): The amount of the token to borrow.
+ * - `baseTokenSymbol` (string): The symbol of the token to borrow (e.g., "BTC").
+ *
+ * Output:
+ * - Success: Returns a success message confirming the borrowed amount.
+ * - Failure: Returns an error message with the appropriate HTTP status code.
+ *
+ * Workflow:
+ * 1. Validates input parameters (`userId`, `borrowAmount`, `baseTokenSymbol`).
+ * 2. Calls the `borrow` method in the lending module to:
+ *    - Verify collateral sufficiency.
+ *    - Deduct the borrowed tokens from the liquidity pool.
+ *    - Increase the user's debt.
+ *    - Credit the borrowed tokens to the user's wallet.
+ * 3. Returns a response with the result of the borrowing operation.
+ *
+ *
+ * Example Request:
+ * ```json
+ * {
+ *   "userId": "user1",
+ *   "borrowAmount": 150,
+ *   "baseTokenSymbol": "BTC"
+ * }
+ * ```
+ *
+ * Example Response:
+ * ```json
+ * {
+ *   "statusCode": 200,
+ *   "body": "Borrowed 150 of token BTC against collateral."
+ * }
+ * ```
+ */
+export function borrowEndpoint(request: ccfapp.Request): ccfapp.Response {
+    let body;
+    try {
+        body = request.body.json();
+    } catch {
+        return { statusCode: 400, body: "Invalid request body" };
+    }
+
+    const { userId, borrowAmount, baseTokenSymbol } = body;
+
+    // Validate input parameters
+    if (!userId || !baseTokenSymbol || borrowAmount <= 0) {
+        return { statusCode: 400, body: "Invalid input parameters" };
+    }
+
+    try {
+        // Attempt to borrow tokens using the lending logic
+        const result = borrow(userId, borrowAmount, baseTokenSymbol);
+
+        return { statusCode: 200, body: result };
+    } catch (error) {
+        return handleError(error);
+    }
+}